Method and system for providing improved wireless audio transmission

Abstract

A method and system for providing improved confined area audio amplification is provided. Designed to meet the requirements of classrooms, conference rooms and offices, this new invention provides improved signal-to-noise ratio, improved system redundancy, and higher voice audio quality than is offered in previous systems. This invention utilizes infrared as the wireless communications channel, and does so with two receivers, a master and a slave to provide redundancy in signal reception and thereby solving one of the long standing problems with line of sight communications systems. This invention also employs a pulse position modulated signal which has higher noise and interference immunitity that is available with prior systems. This invention is flexible with a lightweight, wireless, battery operated transmitter packaged in a necklace type of holder, suitable for wearing around the neck of the speaker. This invention employs speech processing techniques to improve the sound quality and clarity of human speech audio. This invention is further innovative in its combination of features that are focused on solving the problem of amplification of speech in a confined area.

We claim: 
     
       1. A wireless communications system for classroom use, comprising: (a) a portable transmitter for transmitting an infrared pulse position modulated signal;   (b) a receiver for receiving said infrared pulse position modulated signal and converting said infrared pulse position modulated signal into an output electrical signal, wherein said receiver further comprises: (i) a master receiver for receiving said infrared pulse position modulated signal when a direct line of sight exists between said transmitter and said master receiver, wherein said master receiver further comprises: (1) at least one photodiode for receiving said infrared pulse position modulated signal and producing an electrical pulse position modulated signal;   (2) a high gain pre-amplifier receiving said electrical pulse position modulated signal and producing an amplified modulated signal;   (3) a high pass filter/amplifier receiving said amplified modulated signal and producing a filtered signal;   (4) an amplifier receiving said filtered signal and producing an amplified signal;   (5) a demodulator receiving said amplified signal and producing a demodulated signal;   (6) a low pass filter/de-emphasizer receiving said demodulated signal and producing a filtered/de-emphasized signal;   (7) a charge pump receiving said amplified signal of said amplifier and producing a rectifier voltage signal;   (8) a comparator receiving said rectifier voltage signal and a reference voltage and producing at least one control signal;   (9) at least two gates receiving said at least one control signal, said filtered/de-emphasized signal and a signal from a slave receiver and producing an input signal;   (10) a speech processor receiving said input signal and producing an output signal;   (11) a mixer/audio amplifier receiving said output signal and producing an audio output signal; and   (12) at least one audio power amplifier receiving said audio output signal and producing at least one speaker driving output signal; and     (ii) said slave receiver for receiving said infrared pulse position modulated signal when a direct line of sight does not exist between said transmitter and said master receiver; and     (c) a speaker system for receiving said output electrical signal from said receiver and converting said output electrical signal to audible sound.   
     
     
       2. A wireless communications system for classroom use, comprising: (a) a portable transmitter for transmitting an infrared pulse position modulated signal;   (b) a receiver for receiving said infrared pulse position modulated signal and converting said infrared pulse position modulated signal into an output electrical signal wherein said receiver further comprises: (i) a master receiver for receiving said infrared pulse position modulated signal when a direct line of sight exists between said transmitter and said master receiver; and   (ii) a slave receiver for receiving said infrared pulse position modulated signal when a direct line of sight does not exist between said transmitter and said master receiver wherein said slave receiver further comprises: (1) at least one photodiode for receiving said infrared pulse position modulated signal and producing an electrical pulse position modulated signal;   (2) a high gain pre-amplifier receiving said electrical pulse position modulated signal and producing an amplified modulated signal;   (3) a high pass filter/amplifier receiving said amplified modulated signal and producing a filtered signal;   (4) an amplifier receiving said filtered signal and producing an amplified signal;   (5) a demodulator receiving said amplified signal and producing a demodulated signal;   (6) a low pass filter/de-emphasizer receiving said demodulated signal and producing a filtered/de-emphasized signal;   (7) a charge pump receiving said amplified signal of said amplifier and producing a rectifier voltage signal;   (8) a comparator receiving said rectifier voltage signal and a reference voltage and producing at least one control signal; and   (9) a gate receiving said at least one control signal, and said filtered/de-emphasized signal, and producing an input signal for said master receiver; and       (c) a speaker system for receiving said output electrical signal from said receiver and converting said output electrical signal to audible sound.   
     
     
       3. A wireless communications system for classroom use, comprising: (a) a portable transmitter for transmitting an infrared pulse position modulated signal, wherein said portable transmitter further comprises: (i) a battery pack device to provide portable energy to operate said transmitter;   (ii) a necklace device suitable for wearing around the neck of a user, said necklace device having incorporated on its surface at least one infrared light emitting diode;   (iii) a microphone device attached to said necklace device to convert audible sound to an input electrical signal;   (iv) a pre-amplifier receiving said input electrical signal and amplifying said input electrical signal, received from said microphone device, into a pre-amplified signal;   (v) a speech processor receiving said pre-amplified signal and compressing said pre-amplified signal into a compressed audio signal, wherein said speech processor further comprises: (1) a voltage controlled amplifier receiving said pre-amplified signal and producing an amplified audio signal;   (2) an amplifier and response control circuit receiving said amplified audio signal and producing said compressed audio signal;   (3) an amplifier receiving said pre-amplified signal and producing a pre-rectified signal; and   (4) a rectifier receiving said pre-rectified signal and producing a control signal to control said voltage controlled amplifier;     (vi) a buffer receiving said compressed audio signal, modulating said compressed audio signal into a modulated audio signal;   (vii) a pulse generator receiving said modulated audio signal and producing an electrical pulse position modulated signal; and   (viii) said at least one infrared light emitting diode attached to said necklace, receiving said electrical pulse position modulated signal and producing said infrared pulse position modulated signal for transmission to a receiver;     (b) said receiver for receiving said infrared pulse position modulated signal and converting said infrared pulse position modulated signal into an output electrical signal; and   (c) a speaker system for receiving said output electrical signal from said receiver and converting said output electrical signal to audible sound.   
     
     
       4. A wireless communications system for classroom use, comprising: (a) a portable transmitter for transmitting an infrared pulse position modulated signal;   (b) a receiver for receiving said infrared pulse position modulated signal and converting said infrared pulse position modulated signal into an output electrical signal, wherein said receiver further comprises: (i) a master receiver for receiving said infrared pulse position modulated signal when a direct line of sight exists between said transmitter and said master receiver, wherein said master receiver further comprises: (1) at least one photodiode for receiving said infrared pulse position modulated signal and producing an electrical pulse position modulated signal;   (2) a high gain pre-amplifier receiving said electrical pulse position modulated signal and producing an amplified modulated signal;   (3) a high pass filter/amplifier receiving said amplified modulated signal and producing a filtered signal;   (4) an amplifier receiving said filtered signal and producing an amplified signal;   (5) a demodulator receiving said amplified signal and producing a demodulated signal;   (6) a low pass filter/de-emphasizer receiving said demodulated signal and producing a filtered/de-emphasized signal;   (7) a charge pump receiving said amplified signal of said amplifier and producing a rectifier voltage signal;   (8) a comparator receiving said rectifier voltage signal and a reference voltage and producing at least one control signal;   (9) at least two gates receiving said at least one control signal, said filtered/de-emphasized signal and a signal from a slave receiver and producing an input signal;   (10) a speech processor receiving said input signal and producing an output signal, wherein said speech processor further comprises: (a) a voltage controlled amplifier receiving said input signal and producing an amplified audio signal;   (b) an amplifier and response control circuit receiving said amplified audio signal and producing a decompressed audio signal;   (c) an amplifier receiving said input signal and producing an pre-rectified signal; and   (d) a rectifier receiving said pre-rectified signal and producing a control signal to control said voltage controlled amplifier;     (11) a mixer/audio amplifier receiving said output signal of said speech processor and producing an audio output signal;   (12) at least one audio power amplifier receiving said audio output signal and producing at least one speaker driving output signal; and     (ii) said slave receiver for receiving said infrared pulse position modulated signal when a direct line of sight does not exist between said transmitter and said master receiver; and     (c) a speaker system for receiving said output electrical signal from said receiver and converting said output electrical signal to audible sound.